Stimulating pancreatic alpha cells causes them to secrete the hormone glucagon, which primarily leads to an increase in blood glucose levels throughout the body.
When the specialized alpha cells within the pancreatic islets of Langerhans are activated, their immediate response is to release glucagon. This hormone serves as a critical counter-regulatory agent to insulin, primarily acting to prevent or correct low blood sugar (hypoglycemia).
How Glucagon Elevates Blood Glucose
Glucagon's main target organ is the liver, where it triggers a vital process for glucose mobilization:
- Glycogenolysis: Glucagon stimulates the liver to rapidly convert its stored glycogen—a complex carbohydrate and the body's primary glucose reserve—back into individual glucose molecules. This breakdown process is scientifically known as glycogenolysis.
- Glucose Release into Circulation: Once the glycogen is broken down, the newly freed glucose is then released directly from the liver into the bloodstream. This immediate influx of glucose makes it readily available for all body cells to use as an energy source, especially critical for organs like the brain, which rely almost exclusively on glucose for fuel.
This mechanism ensures that the body can maintain stable blood glucose levels, even during periods of fasting or when dietary glucose intake is insufficient.
Summary of the Physiological Response:
| Event | Description |
|---|---|
| 1. Alpha Cell Stimulation | Pancreatic alpha cells receive a signal (often due to low blood glucose) to become active. |
| 2. Glucagon Secretion | The stimulated alpha cells release the hormone glucagon into the bloodstream. |
| 3. Liver Action (Glycogenolysis) | Glucagon travels to the liver, its primary target, and initiates the breakdown of stored glycogen into glucose molecules. |
| 4. Glucose Release | The newly produced glucose is then released from the liver's stores directly into the general circulation. |
| 5. Increased Blood Glucose | This leads to a rise in the overall blood glucose concentration, providing necessary energy for all body cells and maintaining metabolic homeostasis. |
For more detailed information on glucagon and its functions, you can refer to reputable sources such as the Cleveland Clinic: Glucagon: What It Is, Function & Side Effects.
